We plan to synthesize novel nucleosides as potential antitumor agents. Our approach will be to prepare nucleoside derivatives of enaminonitriles and study the photochemical cyclization of the enaminonitriles to heterocyclic derivatives of ribose. This may provide a novel approach to the synthesis of nucleosides which are not available by conventional methods of synthesis. We will also study the mechanism of this photochemical rearrangement and related rearrangements by variety of physical techniques including flash photolysis and epr spectrometry.